The rover is the size of a small car, so engineers had to come up with a new way to set it down. For the first time, cables were used to lower the rover inside of a giant crater.

At $2.5 billion, it's the most ambitious and priciest Mars mission yet. For the next two years, the rover will drill into rocks and scoop up soil. It will be exploring whether the planet's environment could have supported life in the form of microscopic organisms.